The present invention is generally related to wireless communications and, more particularly, to a method of conserving mobile station battery power in the wireless network communicating packets of information to and from a mobile station.
FIG. 1 illustrates a prior art algorithm for packet switched communications. Typically, user requests for the transfer of information are processed through a higher-level software routine which coordinates a logical connection to the base station or communicating server, requests a traffic channel to transfer data, and requests the data be formatted for communication on the traffic channel, using the packet switched communication method. In Step 10, when the application program requests a data transfer, the mobile station initiates a call with an indication that a packet switched communication (a packet call) is to be established. In Step 12 a circuit switched connection is established by occupying a radio channel assigned by the base station. Typically, the connection is a type of circuit switched connection called a packet switched connection. Whereas a circuit switched connection maintains the physical connection until the physical connection is broken by either the base or mobile station, a packet switched connection permits the physical connection to be broken in between data transfers. Alternately stated, a packet switched connection is a series of circuit switched connections.
In Step 14 the mobile station starts negotiation process with the system using protocols such as transmission control protocol (TCP) to establish the logical protocol connections. Typically, a TCP protocol implies the connection of the base station to at least one server through a packet network. Radio link protocols (RLP) and point-to-point protocols (PPP) more directly concern the link between the mobile station and the base station, which is typically the subject of Step 14. In Step 16 the mobile station resets the inactive timer, and starts the data transfer in Step 18.
In Step 20 the mobile station monitors an arrival of data, either from the base station or from the application program. That is, either the user (through the applications program), or the communicating base station, can request the initiation of data transfer. The inactive timer is reset the arrival of data in Step 16. During data transfer, the mobile station repeatedly checks the status of the inactive timer (Step 22). If the timer does not expire (xe2x80x9cNoxe2x80x9d, Step 22), the mobile station continues monitoring the arrival of data by returning to Step 20 of the process. If the timer expires (xe2x80x9cYesxe2x80x9d, Step 22), the mobile station considers that the data transfer is finished, disconnects the packet call, and terminates the circuit switched connection by proceeding to Step 24. The mobile station then enters into a type of standby mode where the mobile continues to monitor base station control signals. In Step 26 the mobile station periodically monitors the forward link signal (signal from the base station).
In the standby mode, while maintaining the logical protocol connections, the mobile station waits for either of the following two events. Alternately, the mobile station may have a dormant type standby mode where the mobile station monitors the base station less frequently. If, in Step 28 there is no page by the base station (No), the process proceeds to Step 30. If, in Step 30 there is no data to send (No), the process returns to Step 26. If there is an arrival of data from the application program in Step 30 (Yes), the process proceeds to Step 32. In Step 32 the call is initiated by the mobile station, and the packet switched connection is re-established in Step 34.
If, in Step 28 a packet call is received, originated by the base station (Yes), the mobile station accepts the packet call in Step 36 and proceeds to Step 34. Regardless of how the process reaches Step 34, the inactive timer is reset in Step 16, the data transfer is started in Step 18.
Typical application programs using the above-described method of FIG. 1 are Internet type applications, such as Web browsers and e-mail readers. In such application programs, the communication between the mobile station and the base station consists of a series of data transfer sessions. A session begins when the user of the application program requests access to a homepage or e-mail account, and ends when all the requested data is transferred to the application program. Typically, the session is initiated by the user of the application program, not by any entity of the network, including the cellular communication system, or any network or internet server. In other words, once a session of data transfers is finished, the next data transfer will not happen until the user requests another session. However, prior art mobile stations are required to activate receiver circuitry, periodically monitoring the forward link signal after the end of a session, in search of a request from the base station (Step 28 of FIG. 1), even though such a request will never come. The constant monitoring process by the mobile station wastes battery power.
Some prior art system have developed communication protocols to reduce the mobile station monitoring of base station control messages in some special circumstances. These designs reduce the mobile station""s power consumption to the extent that the monitoring process is reduced. For example, in U.S. Pat. No. 5,590,396, invented by Henry, a method of power saving is disclosed which places the mobile station into a pager-only mode, with periodically wake-ups to receive short messages from a base station. In U.S. Pat. No. 5,627,882, invented by Chien et al., power is saved by changing the duration of sleep, or reduced mobile station monitoring times based on the standby time history. In U.S. Pat. No. 5,560,021, invented by Vook et al., a wireless local area network (LAN) power management system is disclosed having a periodic active mode, where indicator signals are transmitted to inform the specific devices if data is forthcoming. Devices not receiving an indicator signal are permitted to enter a sleep mode. All the above-mentioned devices use at least some power in monitoring the base station control signals.
It would be advantageous if a wireless packet information system could conserve mobile station battery power through the elimination of unnecessary monitoring of the base station control signals.
It would be advantageous if a mobile station could conserve battery power by breaking the physical channel to a communication base station in between packet information sessions.
It would be advantageous if a mobile station could enter a dormant, low-power consumption mode when the physical connection is temporarily disabled, even if the logical protocol connection is still established.
Accordingly, in a communications system including a base station and at least one mobile station, a method has been provided for the mobile station to organize the transfer of information with the base station. The method comprises the steps of:
a) energizing the mobile station receiver when information is to be transferred;
b) disabling the mobile station receiver when no information is to be transferred; and
c) maintaining the disabled state of the mobile station receiver until the mobile station receives another request from the user interface to transfer information. Battery power and system processing time are conserved by not monitoring the link to the base station between information transfer tasks.
Typically, the data transfer process is initiated through a request from the mobile station user interface. Likewise, following Step a), the mobile station accepts a request from the user interface to end the transfer of information. The user interface may be in the form of an application program, such as a web browser, which initiates requests for data. The application program signals the end of an information request.
The physical connection enabling the transfer of information between the base station and the mobile station in Step a) utilizes a plurality of data messages on a traffic channel. The complete set of data messages which transfers the information is called an information session. Step b), therefore, disables the mobile station receiver at the end of the information session, so that no further messages are sent on the traffic channel. As is well known, the traffic channel may be in the form a channel distinguished by an orthogonal code, carrier frequency, modulation frequency, or timing. Likewise, Step a) includes the timing and channels of the data messages between the base station and the mobile station being dependent on a plurality of control messages between the base and mobile stations. Step b) disables the control message monitoring of the base station by the mobile station, and Step c) maintains the disabled state of control message monitoring by the mobile station, until the mobile station receives another request from the user interface to transfer information.